外加气流法制备微相结构有序的PS-b-PEO嵌段共聚物薄膜

Preparation of Oriented PS-b-PEO Block Copolymer Membranes by Air-flow Method

采用原子转移自由基聚合（ATRP）的方法合成了聚苯乙烯-聚环氧乙烷（PS-b-PEO）嵌段共聚物,并利用核磁共振波谱（1H-NMR）、傅里叶变换红外光谱（FTIR）以及凝胶渗透色谱法（GPC）对聚合物进行了表征.利用外加气流法制备了具有不同形貌的嵌段共聚物薄膜,并讨论聚合物分子组成、气流温度、气流速度以及不同基底对薄膜表面形貌以及内部结构的影响.当嵌段共聚物中聚苯乙烯嵌段的质量分数为83%～85%,气流温度为30～50℃,气流速度3～5 m/s时,有利于形成表面垂直柱状微相分离结构.当硅基底的接触角小于90°时,在合适的外加气流场作用下可以形成薄膜的表层和底层垂直有序而薄膜内部无序的非对称结构。

A new and facile air-flow method was employed to prepare block copolymer membranes with different morphology. PS-b-PEO block copolymers were synthesized by atom transfer radical polymerization（ ATRP）. The molecular characteristics of the block copolymers were confirmed by1H-NMR,FTIR spectroscopy and gel permeation chromatography（ GPC）. AFM and SEM were employed to characterize the surface morphology and inner structure of the films. Effects of molecular structure,air-flow velocity,air-flow temperature and substrate affinity on the membrane surface morphology and internal structure were studied.Vertically oriented microphase structure on the top surface of the membrane can be achieved when the PS mass fraction was between 83% and 85%,air-flow temperature was 50 ℃ and air-flow velocity was 4 m /s. When the liquid film was treated with an air speed outside the range of 3 ～ 5 m /s,no regular structure was observed.Similarly,when the air-flow temperature was too high or too low,no regular structure was observed. Substrates with different contact angles were prepared by chemical modification. Results showed that when the films were prepared on silicon substrates with contact angle less than 90° under appropriate air-flow condition,vertical orientation of cylinder nanochannels formed only in the regions at the top and bottom layers of the block copolymer films while irregular structure appeared in the middle part.